* [PATCH 1/8] objtool: Don't report end of section error after an empty unwind hint
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 2/8] x86/head: Remove confusing comment Josh Poimboeuf
` (6 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
If asm code specifies an UNWIND_HINT_EMPTY hint, don't warn if the
section ends unexpectedly. This can happen with the xen-head.S code
because the hypercall_page is "text" but it's all zeros.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
tools/objtool/check.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index f744617c9946..d8683f0fe04d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1737,11 +1737,14 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
if (insn->dead_end)
return 0;
- insn = next_insn;
- if (!insn) {
+ if (!next_insn) {
+ if (state.cfa.base == CFI_UNDEFINED)
+ return 0;
WARN("%s: unexpected end of section", sec->name);
return 1;
}
+
+ insn = next_insn;
}
return 0;
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 2/8] x86/head: Remove confusing comment
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 1/8] objtool: Don't report end of section error after an empty unwind hint Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 3/8] x86/head: Remove unused 'bad_address' code Josh Poimboeuf
` (5 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
This comment is actively wrong and confusing. It refers to the
registers' stack offsets after the pt_regs has been constructed on the
stack, but this code is *before* that.
At this point the stack just has the standard iret frame, for which no
comment should be needed.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kernel/head_64.S | 4 ----
1 file changed, 4 deletions(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 513cbb012ecc..3b04e4c99389 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -270,10 +270,6 @@ bad_address:
__INIT
ENTRY(early_idt_handler_array)
- # 104(%rsp) %rflags
- # 96(%rsp) %cs
- # 88(%rsp) %rip
- # 80(%rsp) error code
i = 0
.rept NUM_EXCEPTION_VECTORS
.ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 3/8] x86/head: Remove unused 'bad_address' code
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 1/8] objtool: Don't report end of section error after an empty unwind hint Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 2/8] x86/head: Remove confusing comment Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 4/8] x86/head: Fix head ELF function annotations Josh Poimboeuf
` (4 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
It's no longer possible for this code to be executed, so remove it.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kernel/head_64.S | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 3b04e4c99389..afb0a1e22d41 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -265,9 +265,6 @@ ENDPROC(start_cpu0)
.quad init_thread_union + THREAD_SIZE - SIZEOF_PTREGS
__FINITDATA
-bad_address:
- jmp bad_address
-
__INIT
ENTRY(early_idt_handler_array)
i = 0
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 4/8] x86/head: Fix head ELF function annotations
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
` (2 preceding siblings ...)
2017-08-31 20:23 ` [PATCH 3/8] x86/head: Remove unused 'bad_address' code Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 5/8] x86/boot: Annotate verify_cpu() as a callable function Josh Poimboeuf
` (3 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
These functions aren't callable C-type functions, so don't annotate them
as such.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kernel/head_64.S | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index afb0a1e22d41..edacd579d504 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -234,7 +234,7 @@ ENTRY(secondary_startup_64)
pushq %rax # target address in negative space
lretq
.Lafter_lret:
-ENDPROC(secondary_startup_64)
+END(secondary_startup_64)
#include "verify_cpu.S"
@@ -277,7 +277,7 @@ ENTRY(early_idt_handler_array)
i = i + 1
.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
.endr
-ENDPROC(early_idt_handler_array)
+END(early_idt_handler_array)
early_idt_handler_common:
/*
@@ -320,7 +320,7 @@ early_idt_handler_common:
20:
decl early_recursion_flag(%rip)
jmp restore_regs_and_iret
-ENDPROC(early_idt_handler_common)
+END(early_idt_handler_common)
__INITDATA
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 5/8] x86/boot: Annotate verify_cpu() as a callable function
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
` (3 preceding siblings ...)
2017-08-31 20:23 ` [PATCH 4/8] x86/head: Fix head ELF function annotations Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 6/8] x86/xen: Fix xen head ELF annotations Josh Poimboeuf
` (2 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
verify_cpu() is a callable function. Annotate it as such.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kernel/verify_cpu.S | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/verify_cpu.S b/arch/x86/kernel/verify_cpu.S
index 014ea59aa153..3d3c2f71f617 100644
--- a/arch/x86/kernel/verify_cpu.S
+++ b/arch/x86/kernel/verify_cpu.S
@@ -33,7 +33,7 @@
#include <asm/cpufeatures.h>
#include <asm/msr-index.h>
-verify_cpu:
+ENTRY(verify_cpu)
pushf # Save caller passed flags
push $0 # Kill any dangerous flags
popf
@@ -139,3 +139,4 @@ verify_cpu:
popf # Restore caller passed flags
xorl %eax, %eax
ret
+ENDPROC(verify_cpu)
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 6/8] x86/xen: Fix xen head ELF annotations
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
` (4 preceding siblings ...)
2017-08-31 20:23 ` [PATCH 5/8] x86/boot: Annotate verify_cpu() as a callable function Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 7/8] x86/xen: Add unwind hint annotations Josh Poimboeuf
2017-08-31 20:23 ` [PATCH 8/8] x86/head: " Josh Poimboeuf
7 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
Mark the ends of the startup_xen and hypercall_page code sections.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/xen/xen-head.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index a7525e95d53f..9753225289e8 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -33,7 +33,7 @@ ENTRY(startup_xen)
mov $init_thread_union+THREAD_SIZE, %_ASM_SP
jmp xen_start_kernel
-
+END(startup_xen)
__FINIT
#endif
@@ -47,7 +47,7 @@ ENTRY(hypercall_page)
.type xen_hypercall_##n, @function; .size xen_hypercall_##n, 32
#include <asm/xen-hypercalls.h>
#undef HYPERCALL
-
+END(hypercall_page)
.popsection
ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz "linux")
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 7/8] x86/xen: Add unwind hint annotations
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
` (5 preceding siblings ...)
2017-08-31 20:23 ` [PATCH 6/8] x86/xen: Fix xen head ELF annotations Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
2017-09-12 12:56 ` Jiri Slaby
2017-08-31 20:23 ` [PATCH 8/8] x86/head: " Josh Poimboeuf
7 siblings, 1 reply; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
Add unwind hint annotations to the xen head code so the ORC unwinder can
read head_64.o.
hypercall_page needs empty annotations at 32-byte intervals to match the
'xen_hypercall_*' ELF functions at those locations.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/xen/xen-head.S | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index 9753225289e8..8f9741cbb32f 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -19,6 +19,7 @@
#ifdef CONFIG_XEN_PV
__INIT
ENTRY(startup_xen)
+ UNWIND_HINT_EMPTY
cld
/* Clear .bss */
@@ -40,7 +41,10 @@ END(startup_xen)
.pushsection .text
.balign PAGE_SIZE
ENTRY(hypercall_page)
- .skip PAGE_SIZE
+ .rept (PAGE_SIZE / 32)
+ UNWIND_HINT_EMPTY
+ .skip 32
+ .endr
#define HYPERCALL(n) \
.equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 7/8] x86/xen: Add unwind hint annotations
2017-08-31 20:23 ` [PATCH 7/8] x86/xen: Add unwind hint annotations Josh Poimboeuf
@ 2017-09-12 12:56 ` Jiri Slaby
2017-09-12 15:39 ` Josh Poimboeuf
0 siblings, 1 reply; 11+ messages in thread
From: Jiri Slaby @ 2017-09-12 12:56 UTC (permalink / raw)
To: Josh Poimboeuf, x86; +Cc: linux-kernel, Andy Lutomirski
On 08/31/2017, 10:23 PM, Josh Poimboeuf wrote:
> Add unwind hint annotations to the xen head code so the ORC unwinder can
> read head_64.o.
xen-head.S is included also in head_32.S, so we see:
arch/x86/kernel/../../x86/xen/xen-head.S:47: Error: no such instruction:
`unwind_hint_empty'
scripts/Makefile.build:413: recipe for target
'arch/x86/kernel/head_32.o' failed
To fix this, I use:
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -25,6 +25,7 @@
#include <asm/bootparam.h>
#include <asm/export.h>
#include <asm/pgtable_32.h>
+#include "../entry/calling.h"
/* Physical address */
#define pa(X) ((X) - __PAGE_OFFSET)
> hypercall_page needs empty annotations at 32-byte intervals to match the
> 'xen_hypercall_*' ELF functions at those locations.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
> arch/x86/xen/xen-head.S | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
> index 9753225289e8..8f9741cbb32f 100644
> --- a/arch/x86/xen/xen-head.S
> +++ b/arch/x86/xen/xen-head.S
> @@ -19,6 +19,7 @@
> #ifdef CONFIG_XEN_PV
> __INIT
> ENTRY(startup_xen)
> + UNWIND_HINT_EMPTY
> cld
>
> /* Clear .bss */
> @@ -40,7 +41,10 @@ END(startup_xen)
> .pushsection .text
> .balign PAGE_SIZE
> ENTRY(hypercall_page)
> - .skip PAGE_SIZE
> + .rept (PAGE_SIZE / 32)
> + UNWIND_HINT_EMPTY
> + .skip 32
> + .endr
>
> #define HYPERCALL(n) \
> .equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \
>
--
js
suse labs
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 7/8] x86/xen: Add unwind hint annotations
2017-09-12 12:56 ` Jiri Slaby
@ 2017-09-12 15:39 ` Josh Poimboeuf
0 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-09-12 15:39 UTC (permalink / raw)
To: Jiri Slaby; +Cc: x86, linux-kernel, Andy Lutomirski
On Tue, Sep 12, 2017 at 02:56:52PM +0200, Jiri Slaby wrote:
> On 08/31/2017, 10:23 PM, Josh Poimboeuf wrote:
> > Add unwind hint annotations to the xen head code so the ORC unwinder can
> > read head_64.o.
>
> xen-head.S is included also in head_32.S, so we see:
> arch/x86/kernel/../../x86/xen/xen-head.S:47: Error: no such instruction:
> `unwind_hint_empty'
> scripts/Makefile.build:413: recipe for target
> 'arch/x86/kernel/head_32.o' failed
>
> To fix this, I use:
>
> --- a/arch/x86/kernel/head_32.S
> +++ b/arch/x86/kernel/head_32.S
> @@ -25,6 +25,7 @@
> #include <asm/bootparam.h>
> #include <asm/export.h>
> #include <asm/pgtable_32.h>
> +#include "../entry/calling.h"
>
> /* Physical address */
> #define pa(X) ((X) - __PAGE_OFFSET)
Thanks. 0-day reported this as well. Will fix this in v2.
--
Josh
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 8/8] x86/head: Add unwind hint annotations
2017-08-31 20:23 [PATCH 0/8] x86/asm: Add unwind hint annotations to head code Josh Poimboeuf
` (6 preceding siblings ...)
2017-08-31 20:23 ` [PATCH 7/8] x86/xen: Add unwind hint annotations Josh Poimboeuf
@ 2017-08-31 20:23 ` Josh Poimboeuf
7 siblings, 0 replies; 11+ messages in thread
From: Josh Poimboeuf @ 2017-08-31 20:23 UTC (permalink / raw)
To: x86; +Cc: Jiri Slaby, linux-kernel, Andy Lutomirski
Jiri Slaby reported an ORC issue when unwinding from an idle task. The
stack was:
ffffffff811083c2 do_idle+0x142/0x1e0
ffffffff8110861d cpu_startup_entry+0x5d/0x60
ffffffff82715f58 start_kernel+0x3ff/0x407
ffffffff827153e8 x86_64_start_kernel+0x14e/0x15d
ffffffff810001bf secondary_startup_64+0x9f/0xa0
The ORC unwinder errored out at secondary_startup_64 because the head
code isn't annotated yet so there wasn't a corresponding ORC entry.
Fix that and any other head-related unwinding issues by adding unwind
hints to the head code.
Reported-by: Jiri Slaby <jslaby@suse.cz>
Tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kernel/Makefile | 1 -
arch/x86/kernel/head_64.S | 14 ++++++++++++--
2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index fd0a7895b63f..d8e2b700d1db 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -26,7 +26,6 @@ KASAN_SANITIZE_dumpstack.o := n
KASAN_SANITIZE_dumpstack_$(BITS).o := n
KASAN_SANITIZE_stacktrace.o := n
-OBJECT_FILES_NON_STANDARD_head_$(BITS).o := y
OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o := y
OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y
OBJECT_FILES_NON_STANDARD_test_nx.o := y
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index edacd579d504..42e32c2e51bb 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -49,6 +49,7 @@ L3_START_KERNEL = pud_index(__START_KERNEL_map)
.code64
.globl startup_64
startup_64:
+ UNWIND_HINT_EMPTY
/*
* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
* and someone has loaded an identity mapped page table
@@ -88,6 +89,7 @@ startup_64:
addq $(early_top_pgt - __START_KERNEL_map), %rax
jmp 1f
ENTRY(secondary_startup_64)
+ UNWIND_HINT_EMPTY
/*
* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
* and someone has loaded a mapped page table.
@@ -132,6 +134,7 @@ ENTRY(secondary_startup_64)
movq $1f, %rax
jmp *%rax
1:
+ UNWIND_HINT_EMPTY
/* Check if nx is implemented */
movl $0x80000001, %eax
@@ -246,6 +249,7 @@ END(secondary_startup_64)
*/
ENTRY(start_cpu0)
movq initial_stack(%rip), %rsp
+ UNWIND_HINT_EMPTY
jmp .Ljump_to_C_code
ENDPROC(start_cpu0)
#endif
@@ -270,13 +274,18 @@ ENTRY(early_idt_handler_array)
i = 0
.rept NUM_EXCEPTION_VECTORS
.ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1
- pushq $0 # Dummy error code, to make stack frame uniform
+ UNWIND_HINT_IRET_REGS
+ pushq $0 # Dummy error code, to make stack frame uniform
+ .else
+ UNWIND_HINT_IRET_REGS offset=8
.endif
pushq $i # 72(%rsp) Vector number
jmp early_idt_handler_common
+ UNWIND_HINT_IRET_REGS
i = i + 1
.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
.endr
+ UNWIND_HINT_IRET_REGS offset=16
END(early_idt_handler_array)
early_idt_handler_common:
@@ -305,6 +314,7 @@ early_idt_handler_common:
pushq %r13 /* pt_regs->r13 */
pushq %r14 /* pt_regs->r14 */
pushq %r15 /* pt_regs->r15 */
+ UNWIND_HINT_REGS
cmpq $14,%rsi /* Page fault? */
jnz 10f
@@ -427,7 +437,7 @@ ENTRY(phys_base)
EXPORT_SYMBOL(phys_base)
#include "../../x86/xen/xen-head.S"
-
+
__PAGE_ALIGNED_BSS
NEXT_PAGE(empty_zero_page)
.skip PAGE_SIZE
--
2.13.5
^ permalink raw reply [flat|nested] 11+ messages in thread